A saltwater fish lives in a hypertonic solution. To survive in this environment, the saltwater fish must consume a lot of seawater and must excrete a lot of excess salts (such as sodium and chloride ions)
Why is this correct?
Saltwater fish, as osmoregulators, reside in a hypertonic environment where the water surrounding them holds a higher salt concentration than their body fluids. Consequently, these fish confront continual challenges of water loss and salt absorption due to osmosis.
Adapting to this environment, saltwater fish need to actively consume significant amounts of water and expel excess salts, including sodium and chloride ions. This essential process allows them to sustain a harmonious equilibrium of water and salts within their bodies, effectively averting dehydration prompted by the osmotic pressure exerted by the encompassing saltwater.